1. Field of the Invention
The present invention relates to an optical member, an optical member producing method, and an image display device. Specifically, the invention relates to an optical member that has high position accuracy for patterns formed with dots having a cholesteric structure, and to a method for producing such an optical member, and to an image display device having the optical member.
2. Description of the Related Art
Materials having a cholesteric structure have wavelength selective reflectivity, and have been used as constituent materials of various optical members by taking advantage of this characteristic. For example, JP-A-2008-238669 describes a pattern printed sheet with a non-visible light reflecting transparent pattern printed on a surface of a water-repellent layer of a substrate comprised of a base and the water-repellent layer. The ink forming the transparent pattern contains a non-visible light reflecting material. The non-visible light reflecting material is a liquid crystal material having a fixed cholesteric structure with wavelength selective reflectivity for the wavelengths of the non-visible light region. The water-repellent layer contains a leveling agent, and has a surface free energy of 40 to 45 mJ/m2. When installed in a display device having an image display capability and used in combination with an input terminal (or an electronic pen as it is commonly called) that is capable of applying and detecting non-visible light such as infrared rays, the pattern printed sheet of this publication is described as being usable as a member that provides a coordinate detecting means that can be suitably used in a data input system of a type that makes input of handwriting data directly through a display device screen.
The present inventors studied the pattern printed sheet provided with the low-surface energy underlayer described in the foregoing publication, and found that, with the configuration of the pattern printed sheet of this publication, the fixed dots with a cholesteric structure will be off-center from the target coordinate positions even when printed in patterns to make the dot center lie on the target coordinate positions. This led to the finding that the configuration of the pattern printed sheet of the related art above involves poor pattern position accuracy in forming a pattern of dots having a cholesteric structure.